Alternating-current electromagnet



E. B. THURSTON.

ALTERNATING CURRENT ELECTROMAGNET.

APPLICATION mm APR. 24. 1911.

1,352,926. PatentedSept. 14, 1920.

FIELI UNITED STATES PATENT oFF cE.

lms'r n. mimsron, or TOLEDO, OHIO, ABSIGNOB TO THE nnuen'ron ELEVATOR AND MACHINE oouramr, or-rronnno, OHIO, A CORPORATION or OHIO.

ALTEQNATING-CUBRENT ELECTROMAGNET.

Specification of Letters Patent. Patented Sept. 14, 1920.

Application filed April 24, 1917. Serial Nit-164,810.

To all 'whom it may concern: 4

Be it known that I, ERNEST B. THURSTON, a citizen of the United States of America, residing at Toledo, Lucas county, Ohio, have invented new and useful Alternatin -Current Electromagnets, of which the 0 owing is a specification.

This invention relates to effecting travel of members from alternating electric current source.

This invention has utility for magnetic actuation of members from remote control source, especially for quieting the throw thereof. I

Referring to the drawings:

Figure 1 is a diagram showing the voltage phase relations with the air ap open between two magnetic members, t e flux therebetween being established from alternating current source of electric supply in the combination of the invention herein disclosed;

Fig. 2 is a second parallelogram difiering from the first in that the air. gap in the magnetic circuit has been reduced, thereby changing the effective phase relations;

Fig. 3 is a graph illustrative of comparative conditions as disclosed in the parallelograms of gigs. 1 and 2 as to the invention herein; and 1 Fig. at is a wiring diagram of an embodiment of the invention.

meter 6, may supply through the line The members 1 and 2 are magnetic with the air gaps 3 therebetween normally maintained by the gravity of the member 2 or as further assisted by the spring The relative travel between the. members 1 and 2 is. limited the m mber 5 and is such that, with the gaps 3 open to a maximum, the

bet'w n the members 1 and 2 is deterined in it is across such air gaps.

A source of alternating current, as the .5611- the coil 8 electrical energy for establishing the magnetic flux between the members 1 and 2 for causing the member 2 to be lifted the alternating electric circuit coil 8 and thereby reduce the air gaps 3.

In series with this coil 8 is the non-inductive resistance 9.

Referring to Fig.3 and considering the line 10-11 as the length of the air gap and the line 10-12 as the pull afiecting thememtion curve between the for opposin travel of the member 2 as sup lemente by the spring 4.

ere the normal alternating current line voltage from line 7 to pass directly through the coil 8 without the resistance 9, the full initial effect on the line voltage would be illustrated by the curve 14, 15, 16, with the considerable pull at the starting point 14.

The section 1415 represents the solenoid pull and the section 15-16 the magnetic pull to scaling position. The drop in the magnetic pull from point It is due to the decrease in the reluctance of the magnetic circuit, which reluctance decreases because the air gap is reduced, As the members move into contacting or close to contacting relation, the acceleration curve 14, 1 5, due to the decreased reluctance of the magnetic circuit action rapidly builds up to its maximum at the closed position.

Accordingly, the action of the acceleraoints 14, 15, is one of decreasing acceleration, which, in the instance of throwing members, as switches, brakes, etc, tends to give the members such a pull that they may be thrown ahead of the acceleration and result in a pound, disastrous to the apparatus.

By the device of thisdisclosure the foregoing disadvantages are automatically overcome and there is created a pick-up for the member to be moved which is of an acceleration, preferred as having a curve with no decreasing action. This end is attained by introducing the non-inductive resistance 9 which, in ccacting with the air gaps 3, may cause initially impressed voltage 17, 18, on the coil-8 to act as shown in Fig. 1 at the angle 18, 17, 19, as to the impressed-voltage 17, 19, on the resistance 9. This wide angle of the starting voltages reduces the efiective voltage or" 17, 20. Taking this as the minimum effective voltage, it may be illustrated by the point 21 on the curve 21, 22, 23, Fig. 3.

As the air gap is reduced, the angle between the phase of the resistance 9 and the phase of coil 8 is increased with the resultant I shortening of the efiective action of the resistance 9, say as shown by the line 2%, 25, Fig. 2, permltting the constant voltage 2%, 26, to materially increase the effective voltage 2, 27, of thecoil 8 as the-air gap is shortened and moving say toward the point 22 on the curve 21, 22, 23. i

There is accordingly provided a magnet having an acceleration for relative travel in reducing the air. gaps 3. The curve of this acceleration has less di than the curve 14, 15, 16. This acceleration curve preferably has its point 22 not less than the point 21, although the point 21 may be less than the point 22. This curve 21, 22, 23, shows the point 21 taking hold above the lme 13 to overcome the condition of rest of the magnet. With very short travel tor the magnet member, say less than one-half inch, this taking hold of the member and pulling it with a force which is not letting the member get away, brings the full thrown position into quick action for positive holding, there bemg entire throw in an effective and quiet manner. The action of the resistance 9 is automatically dec'reasinglyefiective more during the solenoid pull, and is of little eflect durmg the magnetic or sealing pull.

What is claimed and it is desired to secure by Letters Patent is: I

1. A pair of magnetic members providing an air gap therebetween and having means normally tendin to keep the members apart, an alternating e ectric circuit coil having its voltage and current out of phase for establishing a magnetic flux through said mem-' bers, and resistance means in series with said coil having its voltage and amperage in phase.

2. A pair of normally spaced magnetic members, an alternating electric circuit coil for establishing a magnetic flux through said members to reduce the spacing therebe-- tween, and non-inductive means having its resistance at an angle to the resistance of the first coil. 3. A pair of normally spaced magnetic members, an alternating electric circult coil for establishing a magnetic flux through said members to reduce the spacing therebetween, and non-inductive resistance means in series withthe coil having the phase of its resistance at an angle to the'phase of the coil. 4. A pair of normally spaced magnetic members mounted for relative travel toward each other, an alternating electric circuit coil for establishing a magnetic flux through said members to reduce the spacing therebetween, and means having its voltage phase in phase with the amperage of said means and at an angle to the voltage phase of the coil.

5. A pair of normally spaced relatively movable magnetic members disposed for magnetic flux therebetween, an alternating electric circuit coil, and means having its amperage in phase with its voltage and its voltage phase angle as to the voltage phase of the coil varied as the members move.

6. A pair of normally spaced relatively movable magnetic members disposed for magnetic fiux therebetweem an alternating electric circuit coil, and electric mean h ving its voltage phase angle as to the voltage phase of the coil increased as the members approach:

7. A pair of normally spaced relatively movable magnetic members, an alternatlng electric circuit coil for establishing a flux between the members, ,a source of constant voltage current supply, and resistance means in senes with said coil and supply, the voltmembers having magnetic fiux therebetween,

there being first means opposing movement of such members toward each other and second means opposing the action of the first means, said second means including a current coil for establishing magnetic flux between said members andcoacting resistance means inseries with the coil having its effective resistance approach a minimum as magnetic flux between the members reaches a maximum, thereby gradually increasing pull of the members toward each other above the opposing action of the first means.

10. A pair of magnetic members having actuating coil means for a solenoid pull and a magnetic pull, and non-inductive means,

in series with the coil means acting during the solenoid pull.

11. An alternating current circuit, an electro-magnet in said circuit including an inductive resistance coil, a non-inductive resistance in series with said coil and. relatively movable magnetic circuit providing members having an air ap therebetween which members in approac ing sealing position decrease the voltage of the non-induc tive resistance.

12. An alternatingcurrent circuit, an electro-magnet in said circuit including an inductive resistance coil, a non-inductive re sistance in series with said coil and relatively movable magnetic circuit providing members having an air gap therebetween in said coil, which members in approaching sealing position decrease the voltage of the non-inductive resistance.

13.'The method of modifying the action of an electric circuit on a pair of spaced magnetic members comprising magnetizing a circuit in which said members are included by an electric current coil and dampening the action of said coil in the relative movement of the members by a non-inductive resistance having its voltage phase at an angle to the voltage. phase of the coil, and detive and a non-inductive resistance in series creasing said voltage of the resistance as the and varying the coasting effect of the nonmembers approa'ch sealin position by the inductive resistance by changing magnetic 10 increase of the magnetic ux in said memflux at the inductive resistance. 6 bers. In witness whereof I aflix my signature.

14. The method of alternating electric current control including placing an induo- 1 ERNEST B. THURSTON. 

